With the development of semiconductor lighting technology (LED), such new light source has come into our daily life gradually. When the third generation semiconductor material gallium nitride is used as the semiconductor lighting source, its power consumption is only one-tenth of that of a common incandescent lamp under the same brightness; its lifetime can reach more than 1 million hours as well. As a new-type lighting technology, LED can be applied into varieties of fields such as indication, display, decoration, backlight and general lighting due to its numerous advantages including energy conservation, green environmental protection and flexible application etc., which is to bring about a revolution in the lighting field.
At present, most commercial white light LED lighting devices are realized by the cooperation between blue light LED chips and fluorescent powders which are capable of emitting yellow or green-orange light when excited by blue light. Such kind of fluorescent powder has higher luminous efficiency and matured preparation method. However, the light source devices manufactured by this method has the following drawbacks: (1) the epoxy resin for encapsulation ages easily, thus reducing the device lifetime; (2) its process is complex and cost is high; (3) the color coordinate is unstable and the white light is easy to drift.